The invention relates to a process for the production of shaped bodies of plastic material or foamed material, in particular on the basis of polyurethane foam, and a process for the production and/or compacting and/or drying and/or thermoplastic melting of non-woven materials, piles, plastic material fibers, fibers, rubberized hair, rubberized coir, glass fibers or the like which are impregnated, sprayed, wetted and the like with,in particular, thermosetting synthetic resins, for instance polyurethane, latex and the like, with the plastic material or the reactive components or the materials used for the production of the shaped bodies being introduced into a mold and the mold being heated in an inductor during the reaction of the components and the shaping.
In the production of foamed material bodies, in particular those made of polyurethane foam, there are difficulties in the formation of the surface and the completion of the reaction of the components in the surface areas. According to a known process, the reactive components are placed in molds heated by steam or hot air in order to supply the required amounts of heat.This process, however, requires an elaborate apparatus and is inefficient, the heating takes comparatively long and is not optimally controllable.
It has become particularly evident in practice that molds of irregular surface configuration cannot be sufficiently uniformly and quickly heated by means of steam or the like.
It is known to use composite molds for vulcanizing; the frequencies applied there do not require mutual insulation of the individual mold parts, as an uneven heating of the solid and thick parts is not detrimental and the generated heat is to be supplied to the shaped bodies. A precise distribution of temperature over the surface of the shaped bodies is not necessary.
Composite molds consisting of mutually insulated mold parts directly connected to HF electrodes do not permit a precise adjustment of the temperature on the surface of a shaped body, as the penetration depth into the shaped body is too great. For this reason, the working principle does not allow a comparison of devices of this type to devices in which the shaped bodies are produced in an inductor effecting the heating indirectly via the mold walls.